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Batteries wired curiously


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Yesterday I spent a bit of time getting to know the new boat a bit better....

I found that despite the previous owner saying that there wasn't a battery combine switch, in fact, there is. But what's strange is that when the Start battery and combine switches are ON, but the House switch is OFF, the domestics still receive power... turn off the combine switch and they don't, until the House switch is turned ON.

Seems like the combine switch must be bypassing the House isolation switch. Is this normal? Seems odd to me.

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Thanks both.

I have yet to find the CCR. I was planning to install an Add A Battery kit with the automatic charge relay (I installed one of these on my Predator and it's worked faultlessly) which is why I was curious as to the current set up.

 

I noticed on the sea trial that the previous owner ran with the combine switch on, so I wonder if there isn't actually a CCR and he was using the combine switch to enable both batteries to be charged.

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I had mine changed earlier this year, as I had  been running with my change over switch [inside the engine compartment] set to "Both" most of the time and because loads of gear goes on top of the engine box during a trip the switch stayed there. On two occasions I flattened the batteries and had to get assistance.

 

The new control switch was fitted that has an on position, which prioritises after an engine start to recharge the start battery then swings on to the domestic pair.

This means that the switch does not need to be changed during the trip and more importantly the start battery cannot be flattened by the domestic load.

 

Great £350.00 well spent.

 

Until last week when we slept onboard and found out that the auto switching does not work if you let the domestic battery voltage go too low. It charged the start battery but nothing to domestic. The switch does have an manual all battery position that allows normal charging. Good news that we could start the engine, bad news we deep cycled the domestic set again.

 

It sounds like you may have similar switching , so be careful of deep cycling on the domestics.

 

I only had a voltmeter on the instrument cluster that showed start battery volts, I added a second one that now shows volts of the domestic set [£9.00 Amazon and a little bit of wire and work].

Then last week I trickle charged the batteries as slow as possible. Yesterdays trip was good, fingers crossed I have not buggered up two large batteries

 

Charlie

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2 hours ago, Andy135 said:

Thanks both.

I have yet to find the CCR. I was planning to install an Add A Battery kit with the automatic charge relay (I installed one of these on my Predator and it's worked faultlessly) which is why I was curious as to the current set up.

 

I noticed on the sea trial that the previous owner ran with the combine switch on, so I wonder if there isn't actually a CCR and he was using the combine switch to enable both batteries to be charged.

 

After doing some online research, it seems that the DF300 has the ability to charge two batteries separately, which could explain why I haven't seen a CCR/VCR unit. Need to explore this avenue further when I'm at the boat next.

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If the boat hasn't got it already I do recommend volt meters on both batteries that can be seen all the time from the helm, my boat has them and it will quickly show up if one isn't being charged or in a poor state when the engines are off.

 

I've fitted a 190w solar panel which with a MPPT solar charger does a great job of keeping the batteries topped up while at anchor/drifting. If you have room on the roof I'd recommend fitting one. I fitted a Bosch panel (same as on house roofs) about 6 years ago, chosen because it had been tested in salty air. No sign of any corrosion and vastly lower cost than the specialist boat ones.

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Steve, I like the idea of voltmeters. 👍

I found last night that the engine does indeed have the ability to charge two batteries simultaneously and that someone in the boat's past has connected the auxiliary charging wire to the House battery already, which explains why there's no CCR/VCR installed (the engine does this already).

 

I'm still not clear why the Start and Combine switches draw from the House when the House is isolated though. I'm guessing it must be wired incorrectly as it makes no sense and is a drain risk if the House and Start are not truly isolated.

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Hi ,

The latest Suzuki DF 150/350 range will indeed charge two batteries at the same time with two separated outputs from the motor.

The house supply from the motor will be a pink 6mm cable with a ring terminal which should go straight to the house battery positive connection.

I have purchased the kit from Suzuki in order to set mine up for a two battery set up.

Check the motor main fuse box.

The 40amp fuse should be moved from A to B to enable the second charging system.

To avoid damage to the charging system no isolator is to be fitted in the pink cable.

 

Hope this helps

 

Mikey B

 

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Mikey, you're exactly right. Last night I found that on mine the 40a fuse has already been moved from A to B position (switched places with the blanking plug).

 

4GCrKrN.jpg

 

What do you mean by "isolator"? As in an isolating switch in the pink cable? Or a House battery isolator switch?

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Hi Andy,

 

The Pink wire goes directly to the positive post on the house battery only.

The Black Negative wire from the house battery goes to the common Negative connections.

All the battery negatives wire must be connected together.

The battery positive isolator switch must be on the load side only.

Between the battery Positive terminal and the house fuse box.

The motor will charge both batteries at the same time.

You can always give Suzuki UK Marine Technical  Dept a call for further advice.

 

Mikey B

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Thanks again Mikey - what you describe is what appears to be in situ on the boat. As it's a new to me boat I'm trying to ensure that the wiring is as it should be.

 

What's foxing me though is that the domestics have power when the Start isolator and Combine switches are on, but the House isolator is off. Surely if the House is isolated there should be no power to the domestics at all?

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Hi Andy,

 

I think the combined switch should be in the off position?

The combine switch effectively joins both batteries together.

The house isolator should be between the positive and the house fuse box.

With this turned off the house fuse box should be dead (No Power)

 

Turn the combine switch off and see what happens.

 

Mikey B

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Yes, the Combine switch should normally be off, but that's not really my question. What seems strange is that even when the House battery is isolated, power is still getting to the domestics when the Start and Combine switches are turned on. Can anyone help me understand why that should be (other than perhaps a previous owner made a mistake in the wiring)? If the House switch is off, surely the Combine switch can't/shouldn't override that?

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Hi Andy,

 

I'm afraid you will need to trace the Positive cable back from the House fuse box to the House battery Positive terminal.

You should come to the House Battery Isolator.

Anything between and its wired incorrectly.

Then straight to the positive terminal.

 

Mikey B

 

 

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I don't think there is a problem with the way you describe it being wired with the combine switch normally off being wired to bypass the house switch when on.

 

It could have been wired so the house switch had to be on as well, however, there is an advantage the way it's wired, if the house switch fails you can still get power to the domestics.

 

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